Editorial synthesis by the site author across the reading notes below. It is an interpretation, not a finding reported by any single paper. Each note keeps the authors’ findings separate from commentary and links the original source.
Working summary
Temporal interfaces and periodic modulation exchange energy with the field. Floquet descriptions track frequency sidebands and momentum gaps; dispersive time-domain models resolve the switching process.
Connections
The vocabulary of bands and interfaces carries over from spatial crystals, but the conservation laws and energy source change. Parametric amplification connects modulation to source physics.
Draws on the reading notes for: A material changes within an optical cycle, Leaky modes in a driven cavity.
Questions and limits
A single temporal interface is not a time crystal. Microwave, terahertz and optical demonstrations impose very different modulation requirements.